A reactor coolant pump and a reactor coolant system

Abstract

The application provides a reactor coolant pump and a reactor cooling system, wherein the reactor coolant pump comprises a main shaft body, a shaft sleeve, a flywheel, and a support plate. The shaft sleeve is provided with a first through hole, and the main shaft body is connected with the shaft sleeve through the first through hole. The flywheel is a hollow structure, the shaft sleeve is nested in the flywheel, and the flywheel is provided with a first magnet at the bottom. The support plate is provided with a second through hole, the main shaft body is connected with the support plate through the second through hole, the support plate is located at the bottom of the shaft sleeve, one side of the support plate facing the bottom of the flywheel is provided with a second magnet, and the first magnet and the second magnet are homopolar magnets. Due to the repulsion of the homopolar magnets, after the flywheel is caused to rotate at a high speed by the main shaft body and then falls off, the rotating speed of the flywheel gradually decreases, and finally the flywheel is suspended above the support plate, so that the flywheel as a high-energy flying object cannot cause harm to the reactor, the nuclear power unit and other facilities, and the safety of the nuclear power unit is improved.

Description

Technical Field

[0001] This application relates to the field of nuclear power technology, and in particular to a reactor coolant pump and a reactor cooling system. Background Technology

[0002] Reactor coolant pumps are critical equipment in the primary loop of a nuclear power plant, functioning under both normal operation and accident conditions. If a reactor coolant pump unexpectedly loses its motor power input, the coolant cannot circulate properly, causing the heat generated by the reactor to rise in temperature and potentially triggering an accident. To prevent unexpected shutdowns of the coolant pump unit, a flywheel is typically installed. In the event of an unexpected pump shutdown, the energy stored in the flywheel allows the pump unit to continue operating for a period of time to dissipate the heat generated by the nuclear reactor, creating conditions for a potential shutdown of the nuclear power plant.

[0003] Currently, the flywheel in the reactor coolant pump is generally installed on the main pump motor. However, because the flywheel stores a high amount of energy during operation, the main pump unit may operate at overspeed. The increased speed increases the kinetic energy of the flywheel, which may rupture and explode at high speed, producing high-energy projectiles. These high-energy projectiles can cause enormous damage to the reactor, unit, and other facilities, resulting in low safety. Utility Model Content

[0004] This application provides a reactor coolant pump and a reactor cooling system, which can solve the problem of low safety of reactor coolant pumps.

[0005] To solve the above-mentioned technical problems, this application is implemented as follows: In a first aspect, embodiments of this application provide a reactor coolant pump, comprising: Main spindle; A bushing, wherein the bushing has a first through hole, and the main shaft body passes through the first through hole and is connected to the bushing; A flywheel, wherein the flywheel is a hollow structure, the bushing is nested inside the flywheel, and a first magnet is provided on the flywheel; A support plate is provided, and a second through hole is provided on the support plate. The main shaft passes through the second through hole and is connected to the support plate. A second magnet is provided on the side of the support plate facing the bottom of the flywheel. The first magnet and the second magnet are magnets with the same poles.

[0006] Optionally, the thickness of the flywheel in the axial extension direction of the main shaft is less than the thickness of the bushing in the axial extension direction of the main shaft.

[0007] Optionally, the reactor coolant pump further includes a fixing member disposed on the support plate, the support plate having a third through hole, the fixing member passing through the third through hole and connected to the bushing.

[0008] Optionally, the flywheel has a first annular groove at its bottom and the support plate has a second annular groove, wherein the opening direction of the first annular groove is opposite to the opening direction of the second annular groove; The first magnet is located in the first annular groove, and the second magnet is located in the second annular groove.

[0009] Optionally, the top of the flywheel is provided with a third annular groove, the opening direction of which is opposite to the opening direction of the first annular groove; The third annular groove is filled with a filler material, which is a heavy metal.

[0010] Optionally, the bushing has an inverted frustum shape, and the limiting member is a triangular structure on the flywheel that is adapted to the outer wall surface of the bushing. The flywheel is interference-fitted with the inverted frustum shape through the triangular structure.

[0011] Optionally, the vertical projected area of ​​the support plate in the first direction is smaller than the vertical projected area of ​​the flywheel in the first direction.

[0012] Optionally, the bushing, the support plate, and the flywheel are all made of alloy steel.

[0013] Optionally, both the first magnet and the second magnet are high-temperature resistant permanent magnets.

[0014] In a second aspect, embodiments of this application provide a reactor cooling system, including a reactor coolant pump as described in the first aspect.

[0015] In this embodiment, the reactor coolant pump includes: a main shaft; a bushing with a first through hole through which the main shaft passes and connects to the bushing; a flywheel with a hollow structure, the bushing nested inside the flywheel, and a first magnet disposed on the flywheel; and a support plate with a second through hole through which the main shaft passes and connects to the support plate, and a second magnet disposed on the side of the support plate facing the bottom of the flywheel, wherein the first magnet and the second magnet are magnets with the same poles. Due to the repulsive effect of the like poles of the first magnet and the second magnet, when the flywheel is driven to rotate at high speed by the main shaft and causes it to detach, the impact force of the flywheel on the support plate can be reduced. The speed of the flywheel gradually decreases, and it eventually floats above the support plate, preventing the flywheel from becoming a high-energy projectile that could harm the reactor, the unit, and other facilities, thereby improving the safety of the nuclear power unit. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a reactor coolant pump provided in an embodiment of this application. Detailed Implementation

[0017] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0018] Unless otherwise defined, the technical or scientific terms used in this application shall have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms "first," "second," and similar terms used in this application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms "a" or "one," and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms "connected" or "linked," and similar terms, are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right," etc., are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship also changes accordingly.

[0019] The reactor coolant pump and reactor cooling system proposed in the embodiments of the application will be further described below with reference to the accompanying drawings.

[0020] Please see Figure 1 , Figure 1 A schematic diagram of a reactor coolant pump provided in this application embodiment is shown in the figure. The reactor coolant pump includes: Main spindle 10; A bushing 20 is provided, wherein a first through hole 21 is provided, and the main shaft 10 passes through the first through hole 21 and is connected to the bushing 20; The flywheel 30 has a hollow structure, the bushing 20 is nested inside the flywheel 30, and a first magnet 40 is provided on the flywheel 30; The support plate 50 has a second through hole 51. The main shaft 10 passes through the second through hole 51 and is connected to the support plate 50. A second magnet 60 is provided on the side of the support plate 50 facing the bottom of the flywheel 30. The first magnet 40 and the second magnet 60 are magnets with the same poles.

[0021] The aforementioned support plate 50 can be fixed to the main shaft 10 and the bushing 20 respectively by the expansion sleeve and the fixing member 70, and the support plate 50 is located at the bottom of the bushing 20.

[0022] In this embodiment, due to the repulsive effect of the like poles of the first magnet 40 and the second magnet 60, after the flywheel 30 is driven to rotate at high speed by the main shaft 10 and causes the flywheel 30 to fall off, the speed of the flywheel 30 gradually decreases and eventually floats above the support plate 50, thus preventing the flywheel 30 from becoming a high-energy projectile that could harm the reactor, unit and other facilities, thereby improving the safety of the nuclear power unit.

[0023] It should be understood that the reactor coolant pump is a key rotating mechanical device in the reactor cooling system of a pressurized water reactor nuclear power plant. It is a core component driving the circulation of coolant within the primary loop system of the nuclear island and must operate long-term under high temperature, high pressure, and radiation conditions. Its function is to transfer core heat to the steam generator through forced circulation to produce steam, which drives the turbine to perform work, and ensures core cooling is maintained through rotational inertia during a sudden power outage. The maximum kinetic energy that the flywheel 30 can store is determined by its rotational inertia. In an optional embodiment, the rotational inertia of the flywheel 30 can be increased by increasing the mass of its rotor.

[0024] Typically, a reactor coolant pump also includes a housing with a sealed space, and the aforementioned main shaft 10, bushing 20, flywheel 30, and support plate 50 are all located within this sealed space.

[0025] The main spindle 10 is located in the middle of the housing. The bushing 20 has a first through hole 21. The main spindle 10 passes through the first through hole 21 and is connected to the bushing 20. The first through hole 21 and the main spindle 10 are interference fit. In this way, when the main spindle 10 rotates, it can drive the bushing 20 to rotate at the same speed, thereby improving the relative stability between the two.

[0026] The flywheel 30 has a hollow structure, and the bushing 20 is embedded within the hollow structure. Therefore, the main shaft 10, bushing 20, and flywheel 30 are sequentially fitted together. In an optional embodiment, the main shaft 10, bushing 20, and flywheel 30 can all be connected using an interference fit to improve the connection stability between them.

[0027] In an optional embodiment, the flywheel 30 can be a circular ring structure, and the bushing 20 can be an inverted frustum-shaped structure. The outer walls of the flywheel 30 and the bushing 20 have matching inverted frustum-shaped inner surface structures, and the flywheel 30 and the bushing 20 are interference-fitted through the inverted frustum-shaped inner surface structure. In this way, when the main shaft 10 drives the bushing 20 and the flywheel 30 to rotate, the risk of damage to the inner wall of the housing caused by the flywheel 30 at high speed is reduced.

[0028] In an alternative embodiment, the center line of the first through hole 21, the central axis of the bushing 20, and the center line of the flywheel 30 coincide.

[0029] Because different types of reactor coolant pumps result in different structures for the flywheel 30 within the pump body, leading to variations in its installation position. For example, some flywheels 30 are installed at the upper end of the motor, while others are installed at the lower end. By placing a first magnet 40 on the flywheel 30 and a second magnet 60 with the same polarity as the first magnet 40 on the side of the support plate 50 facing the flywheel 30, the flywheel 30 can gradually reduce its rotational speed after detaching from the bushing 20, eventually suspending itself above the support plate 50. This prevents the flywheel 30 from becoming a high-energy projectile that could harm the reactor, unit, and other facilities, thereby improving the safety of the nuclear power unit.

[0030] Optionally, the reactor coolant pump further includes a fixing member 70 disposed on the support plate 50, the support plate 50 having a third through hole 53, the fixing member 70 passing through the third through hole 53 and connected to the bushing 20.

[0031] In this embodiment, by providing a fixing member 70, the support plate 50 is connected to the bushing 20 through the fixing member 70, so that the support plate 50 and the bushing 20 are relatively fixed. In this way, when the main shaft 10 rotates, it can drive the bushing 20 and the support plate 50 to rotate at the same speed.

[0032] Optionally, it may also include a tightening sleeve, and the support plate 50 is connected to the bushing 20 through the fastener 70 and the tightening sleeve, so that the support plate 50 and the bushing 20 are relatively fixed.

[0033] It should be understood that the fixing member 70 can be a fixing screw, and the number of third through holes 53 can be multiple. Multiple third through holes 53 can be evenly spaced around the main shaft 10. Multiple fixing screws correspond one-to-one with multiple third through holes 53. In this way, the fixing screw passes through the third through hole 53 and the bushing 20, and is finally fixedly connected to the bushing 20.

[0034] Optionally, the thickness of the flywheel 30 in the axial extension direction of the main shaft 10 is less than the thickness of the bushing 20 in the axial extension direction of the main shaft 10.

[0035] It should be understood that by setting the thickness of the flywheel 30 to be less than the thickness of the bushing 20, a gap is created between the flywheel 30 and the support plate 50. Assuming the thickness difference between the flywheel 30 and the bushing 20 is N, the size of the gap between the flywheel 30 and the support plate 50 is also N.

[0036] In an optional embodiment, the first magnet 40 and the second magnet 60 may be disposed between the gap. In this way, after the flywheel 30 is driven to rotate at high speed by the main shaft 10 and causes the flywheel 30 to detach, the rotational speed of the flywheel 30 gradually decreases, and it eventually floats above the support plate 50, preventing the flywheel 30 from becoming a high-energy projectile that could harm the reactor, unit and other facilities, thereby improving the safety of the nuclear power unit.

[0037] It should be noted that the thickness of the first magnet 40 and the second magnet 60 can be determined based on the magnetic permeability and magnetic moment of the selected magnet material, as well as the gap between the flywheel 30 and the support plate 50.

[0038] In another optional embodiment, the flywheel 30 is provided with a groove, and correspondingly, the side of the support plate 50 facing the flywheel 30 is also provided with a groove. The first magnet 40 is located in the groove of the flywheel 30, and the second magnet 60 is located in the groove of the support plate 50. In this way, when the main shaft 10 drives the flywheel 30 to rotate at high speed and causes the flywheel 30 to fall off, due to the repulsive effect of the first magnet 40 and the second magnet 60, the rotational speed of the flywheel 30 gradually decreases, and it eventually floats above the support plate 50, preventing the flywheel 30 from becoming a high-energy projectile that could harm the reactor, unit, and other facilities, thereby improving the safety of the nuclear power unit.

[0039] It should be noted that since the flywheel 30 can be set at the upper end or the lower end of the motor, the magnitude of the impact force on the support plate 50 is also different.

[0040] When the flywheel 30 is mounted on the upper end of the motor, a first magnet 40 is provided at the bottom of the flywheel 30, and a second magnet 60 is provided on the side of the support plate 50 facing the bottom of the flywheel 30. In this way, when the main shaft 10 drives the flywheel 30 to rotate at high speed and causes the flywheel 30 to fall off, the impact force of the flywheel 30 on the support plate 50 due to gravity and inertia can be reduced, thereby reducing the impact force on the pump motor located at the bottom of the support plate 50, and thus improving the safety of the reactor coolant pump.

[0041] When the flywheel 30 is installed at the lower end of the motor, i.e., the support plate 50 is located on top of the flywheel 30, the first magnet 40 can be placed on top of the flywheel 30, while a second magnet 60 is placed on the side of the support plate 50 facing the top of the flywheel 30. The two magnets are like-pole repulsive magnets. In this way, when the main shaft 10 drives the flywheel 30 to rotate at high speed, causing the flywheel 30 to detach from the bushing 20, the impact force of the flywheel 30 on the top support plate 50 due to inertia can be reduced, thereby reducing the impact force on the pump motor located on top of the support plate 50, and thus improving the safety of the reactor coolant pump.

[0042] The following description uses the example of the flywheel 30 being located at the top of the motor to illustrate the structure of the reactor coolant pump.

[0043] Optionally, the flywheel 30 is provided with a first annular groove 31 at its bottom, and the support plate 50 is provided with a second annular groove 52, wherein the opening direction of the first annular groove 31 is opposite to the opening direction of the second annular groove 52. The first magnet 40 is located in the first annular groove 31, and the second magnet 60 is located in the second annular groove 52.

[0044] It should be understood that the center lines of the first annular groove 31 and the second annular groove 52 can coincide with the center line of the main shaft 10.

[0045] In this embodiment, by setting the center lines of the first annular groove 31 and the second annular groove 52 to coincide with the center line of the main shaft 10, the repulsive force between the two magnets experienced by the flywheel 30 when it falls off is more balanced, thereby improving the safety of the reactor coolant pump.

[0046] It should be noted that the inner and outer ring diameter parameters of the first magnet 40 and the second magnet 60 can also be determined based on the magnetic permeability and magnetic moment of the selected magnet material, as well as the gap between the flywheel 30 and the support plate 50.

[0047] Since the operating speed of the main shaft 10 of the reactor coolant pump is constant, the maximum kinetic energy that the flywheel 30 can store is determined by its moment of inertia. In an alternative embodiment, the moment of inertia of the flywheel 30 can be increased by increasing the mass of the flywheel 30 rotor. Because the flywheel 30, as a high-speed rotating component, is enclosed outside the main pump shaft, the size design space of the flywheel 30 is strictly limited.

[0048] In addition, since the medium transported by the reactor coolant pump is always in harsh conditions such as high temperature, high pressure and radiation, there are strict requirements for the selection of materials for the flywheel 30 design.

[0049] In an alternative embodiment, the flywheel 30 is made of steel alloy.

[0050] Furthermore, the size of the flywheel 30 is also limited by the casing space of the reactor coolant pump. In order to ensure the mass of the flywheel 30 and reduce the internal space occupied by the flywheel 30, heavy metal is usually embedded in the middle of the flywheel 30.

[0051] In an optional embodiment, the flywheel 30 is provided with a third annular groove 32 on its top, and the opening direction of the third annular groove 32 is opposite to the opening direction of the first annular groove 31. The third annular groove 32 is filled with a filler material, which is a heavy metal.

[0052] It should be understood that the third annular groove 32 can coincide with the center line of the main shaft 10, and the third annular groove 32 is filled with heavy metal. This increases the weight of the flywheel 30. In other words, when the size design of the flywheel 30 is limited by the internal space of the housing, the volume of the flywheel 30 is reduced, thus the flywheel 30 occupies less space.

[0053] In an optional embodiment, the heavy metal is a tungsten alloy.

[0054] In an optional embodiment, the bushing 20 has an inverted frustum shape, and the limiting member is a triangular structure on the flywheel 30 that is adapted to the outer wall surface of the bushing 20. The flywheel 30 is interference-fitted with the inverted frustum shape through the triangular structure.

[0055] In this embodiment, the bushing 20 is designed as an inverted frustum shape, meaning the top area of ​​the bushing 20 is larger than its bottom area. The limiting member on the flywheel 30 is a triangular structure adapted to the inverted frustum shape, with the apex of the triangular structure abutting the top of the bushing 20 and the bottom of the triangular structure abutting the bottom of the bushing 20. Thus, by setting an interference fit between the bushing 20 and the flywheel 30, the reactor coolant pump, at its rated speed and below the speed at which the flywheel 30 detaches, can be driven to rotate by the frictional force of the interference fit between the flywheel 30 and the main shaft 10, storing energy.

[0056] In an optional embodiment, the bushing 20 has an inverted frustum shape, and the flywheel 30 and the outer wall of the bushing 20 have a matching inverted frustum inner surface structure. The flywheel 30 is interference-fitted with the inverted frustum outer surface structure of the bushing 20 through the inverted frustum inner surface structure.

[0057] In this embodiment, the bushing 20 is designed as an inverted frustum shape, meaning the top area of ​​the bushing 20 is larger than its bottom area, and the flywheel 30 and the outer wall of the bushing 20 have a matching inverted frustum inner surface structure. Thus, by setting the bushing 20 and the flywheel 30 in an interference fit connection, the reactor coolant pump, at its rated speed and below the speed at which the flywheel 30 may detach, can be driven to rotate by the frictional force of the interference fit between the flywheel 30 and the main shaft 10, storing energy. It also facilitates removal and reinstallation after the flywheel 30 detaches during high-speed operation.

[0058] Optionally, the vertical projected area of ​​the support plate 50 in the first direction is smaller than the vertical projected area of ​​the flywheel 30 in the first direction.

[0059] It should be understood that the first direction can be the axial extension direction of the main shaft 10. Specifically, the cross-sectional area of ​​the support plate 50 is smaller than that of the flywheel 30, which can reduce the risk of damage to the inner wall of the housing when the support plate 50 rotates. In addition, from an economic point of view, it can also save the materials used to manufacture the support plate 50.

[0060] Optionally, the bushing 20, the support plate 50, and the flywheel 30 are all made of alloy steel.

[0061] Optionally, both the first magnet 40 and the second magnet 60 are high-temperature resistant permanent magnets.

[0062] It should be understood that since the medium transported by the reactor coolant pump is always in harsh conditions such as high temperature, high pressure, and radiation, the service life of the first magnet 40 and the second magnet 60 can be improved by setting the first magnet 40 and the second magnet 60 to high temperature resistant permanent magnets.

[0063] Among them, there are currently four main types of high-temperature resistant magnets that can be used in high-temperature working environments: neodymium iron boron magnets, samarium cobalt magnets, ferrite magnets, and alnico magnets.

[0064] It should be noted that the first magnet 40 and the second magnet 60 can be any one or two of the four commonly used types mentioned above, or other high-temperature resistant permanent magnets. This embodiment does not limit the types of magnets used.

[0065] In an optional embodiment, the nuclear power plant main pump (i.e., the aforementioned reactor coolant pump) includes a main pump shaft, a shaft sleeve, a nested flywheel, and a tray. The nested flywheel is a detachable flywheel.

[0066] The nested flywheel consists of an inner layer of heavy tungsten alloy, an outer layer of alloy steel, a flywheel blocking ring, and an upper magnet. The inner layer of heavy tungsten alloy is nested inside the outer layer of alloy steel, with an interference fit between the inner and outer layers. The flywheel and the bushing are also interference-fitted. The upper magnet is ring-shaped and repels the lower magnet. It is evenly distributed at the bottom of the flywheel, with an interference fit between the upper magnet and the flywheel.

[0067] The inner layer material of the nested flywheel is a heavy tungsten alloy, or other heavy metals. It has a circular or other structure, and its cross-section can be rectangular or other shapes.

[0068] The outer material of the nested flywheel is alloy steel, which is commonly used in nuclear power main pumps. The surface shape of the nested flywheel, which is interference-fitted with the bushing, is an inverted frustum shape. This shape is conducive to the flywheel falling off at ultra-high speeds and to reinstalling after falling off.

[0069] The upper magnet is arranged in a groove specifically designed for the nested flywheel and consists of two annular high-temperature resistant permanent magnets. The high-temperature resistant permanent magnets can be AlNiCo permanent magnets, Samarium Cobalt permanent magnets, or other high-temperature resistant permanent magnets. The cross-section of the permanent magnets can be rectangular or other shapes. The upper magnet and the flywheel are interference-fitted. When the flywheel falls off, the upper magnet and the lower magnet repel each other, thereby reducing the impact of the flywheel on the tray.

[0070] Optionally, the bushing is fixed to the main pump shaft by a shrink sleeve and is in the shape of an inverted frustum.

[0071] Optionally, the tray consists of a tray body, a lower magnet, and a fixing stud. The tray is fixed to the main pump shaft and the shaft sleeve by an expansion sleeve and a fixing stud, respectively. The lower magnet is evenly arranged in a specially designed groove in the tray.

[0072] The tray has a dedicated groove for the magnet, and there is a small gap between the tray and the nested flywheel.

[0073] The lower magnet is arranged in a specially designed groove in the tray and consists of two annular high-temperature resistant permanent magnets. The high-temperature resistant permanent magnets can be AlNiCo permanent magnets, Samarium Cobalt permanent magnets, or other high-temperature resistant permanent magnets. The cross-section of the permanent magnets can be rectangular or other shapes. The lower magnet and the tray are interference-fitted. When the flywheel falls off, the upper magnet and the lower magnet repel each other, thereby reducing the impact of the flywheel on the tray.

[0074] The fixing stud is a countersunk bolt used to fix the tray to the bushing, and the bolt is equipped with an anti-loosening device.

[0075] Optionally, the upper / lower annular high-temperature resistant permanent magnet is characterized in that the shape parameters such as the thickness of the permanent magnet and the diameter of the inner and outer rings are determined according to the magnetic permeability, magnetic moment, and spacing between the upper and lower magnets of the selected high-temperature resistant permanent magnet material.

[0076] In this embodiment, a detachable flywheel for a nuclear power main pump includes a main pump shaft, a bushing, a nested flywheel, and a tray. The nested flywheel consists of an inner layer of heavy tungsten alloy, an outer layer of alloy steel, a flywheel retaining ring, and an upper magnet. The inner layer of heavy tungsten alloy is nested within the outer layer of alloy steel, with an interference fit between the two layers. The flywheel and bushing are also interference-fitted. The upper magnet is annular, repelling the lower magnet, and is evenly distributed on the lower part of the flywheel. The upper magnet and the flywheel are also interference-fitted. The tray consists of a tray body, a lower magnet, and fixing studs. The tray is fixed to the main pump shaft and bushing via expansion sleeves and fixing studs. The lower magnet is annular, repelling the upper magnet, and is evenly distributed on the tray. The lower magnet and the tray are interference-fitted, and the lower magnet is positioned below the upper magnet. The bushing is fixed to the main pump shaft via expansion sleeves. The main pump shaft operates at a constant speed; therefore, the maximum kinetic energy that the flywheel can store is determined by the flywheel's moment of inertia. Increasing the rotational inertia of a flywheel can generally be achieved by increasing the mass of the flywheel rotor. As a high-speed rotating component, the main pump flywheel is enclosed outside the main pump shaft, thus its size design space is strictly limited. Furthermore, the medium transported by the main pump is constantly under harsh conditions such as high temperature, high pressure, and radiation, placing strict requirements on the selection of materials for the main pump flywheel design. Given the strict limitations on flywheel size design space and the stringent requirements on flywheel materials, this application, in order to maintain flywheel mass and reduce the space occupied by the flywheel, embeds a heavy tungsten alloy in the middle of the alloy disc of a typical main pump flywheel. This reduces the flywheel volume while maintaining the same mass, effectively reducing the sealing space occupied by the flywheel.

[0077] In existing nuclear power plants, flywheels are generally mounted on the main pump motor. The installation location varies depending on the flywheel structure; some are mounted on top of the motor, while others are mounted on the bottom. Because flywheels store a high amount of energy during operation, the main pump unit may operate at overspeed. Increased speed increases the flywheel's kinetic energy, and at high speeds, the flywheel may fracture and explode, producing high-energy projectiles. These projectiles pose a potentially huge hazard and consequence to the reactor, the unit, and other facilities.

[0078] In this embodiment, the nuclear power plant main pump operates at normal speed. The flywheel is driven to rotate by the bushing and the main pump shaft through the frictional force of the interference fit. When the speed is too high, the frictional force of the interference fit between the flywheel and the bushing is insufficient, causing the flywheel to detach. After detachment, the upper and lower magnets repel each other to reduce the impact of gravity on the tray. Due to the repulsive force of the upper and lower magnets, the flywheel suspends above the tray and gradually stops, preventing the generation of high-energy projectiles that could harm the reactor, unit, and other facilities.

[0079] This application provides a reactor cooling system, including the reactor coolant pump described above. Since the technical solution of this embodiment includes all the technical solutions of the above embodiments, it can at least achieve all the technical effects of the above embodiments, and will not be repeated here.

[0080] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A reactor coolant pump, characterized in that, include: Main spindle; A bushing, wherein the bushing has a first through hole, and the main shaft body passes through the first through hole and is connected to the bushing; A flywheel, wherein the flywheel is a hollow structure, the bushing is nested inside the flywheel, and a first magnet is provided on the flywheel; A support plate is provided, and a second through hole is provided on the support plate. The main shaft passes through the second through hole and is connected to the support plate. A second magnet is provided on the side of the support plate facing the bottom of the flywheel. The first magnet and the second magnet are magnets with the same poles.

2. The reactor coolant pump of claim 1, wherein, The thickness of the flywheel in the axial extension direction of the main shaft is less than the thickness of the bushing in the axial extension direction of the main shaft.

3. The reactor coolant pump of claim 1, wherein, The reactor coolant pump also includes a fixing member disposed on the support plate, the support plate having a third through hole, the fixing member passing through the third through hole and connected to the bushing.

4. The reactor coolant pump of claim 1, wherein, The flywheel has a first annular groove at its bottom and the support plate has a second annular groove. The opening direction of the first annular groove is opposite to the opening direction of the second annular groove. The first magnet is located in the first annular groove, and the second magnet is located in the second annular groove.

5. The reactor coolant pump of claim 4, wherein, The flywheel is provided with a third annular groove at its top, and the opening direction of the third annular groove is opposite to the opening direction of the first annular groove. The third annular groove is filled with a filler material, which is a heavy metal.

6. The reactor coolant pump of claim 1, wherein, The bushing has an inverted frustum shape, and the flywheel has a triangular structure inside that matches the outer wall of the bushing. The flywheel is interference-fitted with the inverted frustum shape through the triangular structure.

7. The reactor coolant pump according to claim 1, characterized in that, The vertical projected area of ​​the support plate in the first direction is smaller than the vertical projected area of ​​the flywheel in the first direction.

8. The reactor coolant pump of claim 2, wherein, The bushing, the support plate, and the flywheel are all made of alloy steel.

9. The reactor coolant pump according to claim 1, characterized in that, Both the first magnet and the second magnet are high-temperature resistant permanent magnets.

10. A reactor cooling system characterized by, Includes a reactor coolant pump as described in any one of claims 1 to 9.

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